Deleteing from some tables....

Posted on 2000-02-24
Last Modified: 2010-04-04
I have made a simple database containing two tables, one is the master of the other.

The first one is a table of files. The second is a table of discs that these files are stored on.

Files.db and Discs.db.

I have a query for showing this in a TDBGrid with the SQL below:

Select Files.FileName, Discs.Label from Files, Discs
  where Files.Disc = Discs.ID
order by Files.FileName, Discs.Label

This query has an UpdateSQL connected to it.

I also have a separate Query for the discs with the following SQL:

Select ID, Label from Discs

This query is just for showing a list of the discs in a separate TDBGrid.

Now I want to be able to select a disc from the disc-grid and have my program to delete that disc from the database including all of its detail files. For this I have yet another query, the EraserQuery. Here's the SQL for that one:

Delete from Files
  where Disc = :CurrentDisc

"CurrentDisc" is defined below, it is for the program to know which disc the user has selected. -

procedure TModules.DiscQueryBeforeDelete(DataSet: TDataSet);
  EraserQuery.ParamByName('CurrentDisc').AsInteger := Discs.FieldByName('ID').AsInteger;

This works fine with the deletion and all, but it doesn't update the first query, the one showing all files and which disc they're on. It updates the tables and I have to restart my program for it to get updated. What can I do to fix this? Is there a better way deleting detailrecords?


Question by:sageryd
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
  • 2
LVL 27

Expert Comment

ID: 2555031
does a close and reopen of the first query not solve the problem without starting the whole app?

Expert Comment

ID: 2555146
A Refresh should normally do fine.

(Question: Is the query updated when you move a record in the first table and then move back to the record)

Author Comment

ID: 2555345
It works when i close and re-open the first query, but then I lose the selection the use might have. Is there another way? Refresh doesn't work.

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!


Expert Comment

ID: 2555365
Hi sageryd,

perhaps bookmarking it, before closing? (don't know if this works)

Or, get the recordnumber  (thus position of record)

and then after closing do a  

query.First (not needed I think)
query.MoveBy(recordnumber) ?

LVL 27

Accepted Solution

kretzschmar earned 100 total points
ID: 2555533
hi zif,

recordnumber is not on all databases properly filled,
also it is not properly filled, if not all records are fetched.

if zif suggestion will not work,
then save a unique fieldvalue into a var and
after open the query do a locate with it


Author Comment

ID: 2555782
well, ok thanx! I guess Meikl should get the points as he was the first to give an answer.

Thanks again!



Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Introduction Raise your hands if you were as upset with FireMonkey as I was when I discovered that there was no TListview.  I use TListView in almost all of my applications I've written, and I was not going to compromise by resorting to TStringGrid…
If you're a developer or IT admin, you’re probably tasked with managing multiple websites, servers, applications, and levels of security on a daily basis. While this can be extremely time consuming, it can also be frustrating when systems aren't wor…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…

691 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question